Determine the average atomic mass of helium, which has two isotopes having atomic masses 4.0026 amu and 3.0160 amu. The relative abundance of the two isotopes is 99.9999 percent and 0.0001 percent, respectively. A. 1.0066 amu B. 3.0160 amu C. 3.5903 amu D. 4.0026 amu

Two loudspeakers, 5.5 m apart and facing each other, play identical sounds of the same frequency. you stand halfway between them, where there is a maximum of sound intensity. moving from this point toward one of the speakers, you encounter a minimum of sound intensity when you have moved 0.33 m . assume the speed of sound is 340 m/s.part a) what is the frequency of the sound? part b) if the frequency is then increased while you remain 0.21 m from the center, what is the first frequency for which that location will be a maximum of sound intensity? express your answer to two significant figures and include the appropriate units.